Organic light emitting diode display

ABSTRACT

An organic light emitting diode (“OLED”) display includes a semiconductor layer on a substrate, first and second signal lines on the semiconductor layer, a shield layer on the first and second signal lines, a data line on the shield layer, and an OLED on the data line, where the transistor includes a driving transistor, a second transistor connected to the first signal line and the data line, and a third transistor including a gate electrode connected to the first signal line, a third electrode connected to a second electrode of the driving transistor, and a fourth electrode connected to a gate electrode of the driving transistor, the shield layer includes an overlapped portion overlapping at least a part of the connection portion and non-overlaps the second transistor, and the shield layer is separated from the first and second signal lines with a gap therebetween in a plan view.

This application is a continuation of U.S. patent application Ser. No.17/525,136, filed on Nov. 12, 2021, which is a continuation of U.S.patent application Ser. No. 16/697,168, filed on Nov. 26, 2019, whichclaims priority to Korean Patent Application No. 10-2018-0149532, filedon Nov. 28, 2018, and all the benefits accruing therefrom under 35U.S.C. § 119, the content of which in its entirety is hereinincorporated by reference.

BACKGROUND (a) Field

Exemplary embodiments of the invention relate to an organic lightemitting diode (“OLED”) display, and particularly, to an OLED displayfurther including a shield layer.

(b) Description of the Related Art

A display device is a device for displaying images, and recently, anorganic light emitting diode (“OLED”) display has been paid highattention.

The OLED display has a self-emission characteristic, and it does notdesire additional light source, differing from liquid crystal displaydevices, thereby reducing a thickness and a weight thereof. Further, theOLED display has high-quality characteristics such as low powerconsumption, high luminance, and high reaction speed.

The OLED display includes a plurality of signal lines and a plurality ofthin film transistors (“TFT”) connected thereto.

SUMMARY

Exemplary embodiments of the invention have been made in an effort toprovide an organic light emitting diode (“OLED”) display for reducingparasitic capacitance by minimizing an area in which a shield layeroverlaps a semiconductor layer, improving displaying quality, andreducing power consumption.

An exemplary embodiment of the invention provides an OLED displayincluding a substrate, a semiconductor layer disposed on the substrate,on which a channel region, a first region, and a second region of atransistor are provided, a first signal line and a second signal linedisposed on the semiconductor layer, a shield layer disposed on thefirst signal line and the second signal line, a data line disposed onthe shield layer, and an OLED disposed on the data line, where thetransistor includes a driving transistor which applies a current to theOLED, a second transistor which is connected to the first signal lineand the data line, and transmits a data voltage transmitted through thedata line to a first electrode of the driving transistor, and a thirdtransistor including a gate electrode connected to the first signalline, a third electrode connected to a second electrode of the drivingtransistor, and a fourth electrode connected to a gate electrode of thedriving transistor, the third transistor includes a 3-1 transistor and a3-2 transistor connected in series to each other at a connectionportion, the shield layer includes an overlapped portion overlapping atleast a part of the connection portion and does not overlap the secondtransistor, and the shield layer is disposed to be separated from thefirst signal line and the second signal line with a gap therebetween ina plan view.

In an exemplary embodiment, the second signal line may be disposed in asame layer as the first signal line, the shield layer may include anextended portion extending from the overlapped portion, and the extendedportion may extend in parallel to the first signal line and the secondsignal line.

In an exemplary embodiment, the shield layer may receive a drivingvoltage.

In an exemplary embodiment, a first gap that is a minimum distancebetween the shield layer and the first signal line may be 1.2micrometers (μm) to 1.5 μm.

In an exemplary embodiment, a second gap that is a minimum distancebetween the shield layer and the second signal line may be 1.2 μm to 1.5μm.

In an exemplary embodiment, the first signal line may be a scan linewhich transmits a scan signal.

In an exemplary embodiment, the second signal line may be a previousscan line which transmits a previous scan signal.

In an exemplary embodiment, the connection portion may be disposed on aportion where the semiconductor layer is bent.

In an exemplary embodiment, the OLED display may further include a lowervoltage supplying line which is disposed in a same layer as the dataline and supplies the driving voltage.

In an exemplary embodiment, the shield layer may include an expandedportion expanding from the extended portion, and the expanded portionmay receive a driving voltage from the lower voltage supplying line.

In an exemplary embodiment, the OLED display may further include anupper voltage supplying line which is disposed on the lower voltagesupplying line and supplies the driving voltage.

In an exemplary embodiment, the OLED display may further include anauxiliary connecting member disposed in a same layer as the uppervoltage supplying line, and electrically connected to a pixel electrodeof the OLED.

In an exemplary embodiment, the extended portion may overlap at least apart of the upper voltage supplying line.

In an exemplary embodiment, the transistor may include a fourthtransistor connected to the third transistor, and the fourth transistormay include a gate electrode connected to the second signal line and afifth electrode connected to the fourth electrode of the thirdtransistor.

In an exemplary embodiment, the expanded portion of the shield layer mayoverlap at least a part of the fourth transistor.

In an exemplary embodiment, a minimum width of the shield layer may be2.5 pm to 3.3 μm.

Another exemplary embodiment of the invention provides an OLED displayincluding a substrate, a semiconductor layer disposed on the substrate,on which a channel region, a first region, and a second region of atransistor are provided, a first conductive layer disposed on thesemiconductor layer and including a scan line, a second conductive layerdisposed on the first conductive layer, a first data layer disposed onthe second conductive layer and including a data line, and an OLEDdisposed on the first data layer, where the transistor includes adriving transistor which applies a current to the OLED, a secondtransistor which is connected to the scan line and the data line, andtransmits a data voltage transmitted through the data line to a firstelectrode of the driving transistor, and a third transistor including agate electrode connected to the scan line, a third electrode connectedto a second electrode of the driving transistor, and a fourth electrodeconnected to a gate electrode of the driving transistor, the secondconductive layer includes a shield layer, the shield layer overlaps atleast a part of the third transistor and does not overlap the secondtransistor, and the shield layer does not overlap first conductivelayer.

In an exemplary embodiment, the third transistor may include a 3-1transistor and a 3-2 transistor connected in series, and the 3-1transistor and the 3-2 transistor may be connected to each other on aconnection portion.

In an exemplary embodiment, the shield layer may overlap at least a partof the connection portion.

In an exemplary embodiment, a minimum distance between the shield layerand the first conductive layer may be 1.2 μm to 1.5 μm.

According to the exemplary embodiments, the parasitic capacitance isreduced by allowing the shield layer to not overlap a specifictransistor, thereby reducing power consumption of the display device.Further, the display quality may be improved, for example, theafterimage is improved, by reducing a kickback voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other exemplary embodiments, advantages and features ofthis disclosure will become more apparent by describing in furtherdetail exemplary embodiments thereof with reference to the accompanyingdrawings, in which:

FIG. 1 shows a plan view of an exemplary embodiment of an organic lightemitting diode (“OLED”) display.

FIG. 2 shows an enlarged view of part of a pixel shown in FIG. 1 .

FIG. 3 shows a cross-sectional view taken along line of FIG. 2 .

FIG. 4 shows an equivalent circuit diagram of an exemplary embodiment ofa pixel of an OLED display.

FIG. 5 shows a timing diagram of an exemplary embodiment of signalsapplied to a pixel of an OLED display.

DETAILED DESCRIPTION

The invention will be described more fully hereinafter with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown. As those skilled in the art would realize, thedescribed embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the invention.

The drawings and description are to be regarded as illustrative innature and not restrictive. Like reference numerals designate likeelements throughout the specification.

The size and thickness of each configuration shown in the drawings arearbitrarily shown for better understanding and ease of description, andthe invention is not limited thereto. In the drawings, the thickness oflayers, films, panels, regions, etc., are exaggerated for clarity. Forbetter understanding and ease of description, the thicknesses of somelayers and areas are exaggerated.

It will be understood that when an element such as a layer, film,region, or substrate is referred to as being “on” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” another element, there are no intervening elements present. The word“on” or “above” means positioned on or below the object portion, anddoes not necessarily mean positioned on the upper side of the objectportion based on a gravitational direction.

Unless explicitly described to the contrary, the word “comprise” andvariations such as “comprises” or “comprising” will be understood toimply the inclusion of stated elements but not the exclusion of anyother elements.

The phrase “in a plan view” means viewing the object portion from thetop, and the phrase “on a cross-section” means viewing a cross-sectionof which the object portion is vertically cut from the side.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer” or“section” discussed below could be termed a second element, component,region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the content clearly indicatesotherwise. “Or” means “and/or.” As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

An exemplary embodiment of a disposal of a pixel of an organic lightemitting diode (“OLED”) display will now be described with reference toFIG. 1 . FIG. 1 shows a plan view of an exemplary embodiment of an OLEDdisplay.

Referring to FIG. 1 , an exemplary embodiment of one pixel of an OLEDdisplay includes a plurality of signal lines 151, 152, 153, 127, 128,and 171, a plurality of transistors T1, T2, T3 (refer to FIGS. 3 ), T4,T5, T6, and T7 connected to the signal lines, a storage capacitor Cst(refer to FIG. 4 ), voltage supplying lines 172 and 178, and an OLED(refer to FIG. 4 ). The signal lines 151, 152, 153, 127, 128, and 171 orthe voltage supplying lines 172 and 178 may be shared by a plurality ofpixels.

An exemplary embodiment of the OLED display according to the inventionfurther includes a shield layer M, which will be described in a latterportion of the specification.

The transistors include a driving transistor T1, a switching transistorT2, a compensation transistor T3, an initialization transistor T4, anoperation control transistor T5, an emission control transistor T6, anda bypass transistor T7. In an exemplary embodiment, the transistors maybe thin film transistors (“TFTs”), for example

The signal lines may include a scan line 151, a previous scan line 152,an emission control line 153, a bypass control line (not shown), a dataline 171, a lower voltage supplying line 172, a first initializationvoltage line 127, a second initialization voltage line 128, and an uppervoltage supplying line 178. The bypass control line (not shown) may be aprevious scan line 152 or part of the scan line 151, or it may beelectrically connected thereto.

The scan line 151 transmits a scan signal Sn and the previous scan line152 transmits a previous scan signal Sn-1 to the initializationtransistor T4. The bypass control line (not shown) transmits a bypasssignal GB to the bypass transistor T7, and in some exemplaryembodiments, may transmit the same signal as the previous scan signalSn-1 or the scan signal Sn thereto. The emission control line 153transmits an emission control signal EM to the operation controltransistor T5 and the emission control transistor T6.

The data line 171 traverses the scan line 151 and transmits a datasignal Dm. The lower voltage supplying line 172 may transmit a drivingvoltage ELVDD and is provided to be substantially parallel to the dataline 171, and the upper voltage supplying line 178 may be electricallyconnected to the lower voltage supplying line 172 to prevent the lowervoltage supplying line 172 from having a voltage drop. The firstinitialization voltage line 127 may transmit an initialization voltageVint for initializing the driving transistor T1, and the secondinitialization voltage line 128 may transmit an initialization voltageVint for initializing an anode of the OLED.

The transistors T1, T2, T3, T4, T5, T6, and T7 are provided along asemiconductor layer 130 marked with shadows, and the semiconductor layer130 may be provided to be bent in various shapes.

The semiconductor layer 130 includes a channel region (not shown)channel-doped with an N-type impurity or a P-type impurity, and a firstregion and a second region provided on respective sides of a channelhaving a doping concentration that is greater than that of the impuritydoped to the channel. The channel region, the first region, and thesecond region correspond to channels of a plurality of transistors T1,T2, T3, T4, T5, T6, and T7, first electrodes S1, S2, S3, S4, S5, S6, andS7, and second electrodes D1, D2, D3, D4, D5, D6, and D7, and when oneof the first region and the second region is a source region, the othercorresponds to a drain region.

Further, on the semiconductor layer 130, a region between the firstelectrodes S1 to S7 and the second electrodes D1 to D7 of two differenttransistors may be doped so that the two transistors may be electricallyconnected to each other. In exemplary embodiments, the channel may notbe doped with an impurity, and the first region and the second regionmay be doped with impurities.

The respective channel regions of a plurality of transistors T1, T2, T3,T4, T5, T6, and T7 overlap gate electrodes of the transistors, and areprovided between the first regions and the second region thereof.

The plurality of transistors will now be described. The drivingtransistor T1 includes a channel, a gate electrode 155, a firstelectrode S1, and a second electrode D1. The gate electrode 155 overlapsthe channel in a plan view, and the first electrode S1 and the secondelectrode D1 are provided on respective sides of the channel. Anextended portion of the storage line 124 is insulated and provided onthe gate electrode 155. The extended portion of the storage line 124overlaps the gate electrode 155 with a second gate insulating layer(142, refer to FIG. 3 ) therebetween to thus configure a storagecapacitor Cst. The gate electrode 155 is a first electrode (E1 of FIG. 4) of the storage capacitor Cst, and the extended portion of the storageline 124 is a second storage electrode (E2 of FIG. 4 ).

An opening 56 is formed in the extended portion of the storage line 124so that the gate electrode 155 may be connected to a first dataconnecting member 71. In the opening 56, an upper side of the gateelectrode 155 is electrically connected to the first data connectingmember 71 through an opening 61. The first data connecting member 71 isconnected to the second electrode D3 of the compensation transistor T3to connect the gate electrode 155 of the driving transistor T1 and thesecond electrode D3 of the compensation transistor T3.

The gate electrode 155 may, as shown in FIG. 1 , have an island shapethat is separated from the adjacent pixel. The gate electrode 155 may bedisposed in a same layer and with a same material as those of the scanline 151, the previous scan line 152, and the emission control line 153.

The switching transistor T2 may be referred to as a second transistor.

A gate electrode of the switching transistor T2 may be part of the scanline 151. The data line 171 is connected to the first electrode S2 ofthe switching transistor T2 through an opening 62. The switchingtransistor T2 is used as a switching element for selecting a pixel to beemitted. The switching gate electrode is connected to the scan line 151,and the second electrode D2 is connected to the driving transistor T1and the operation control transistor T5.

The compensation transistor T3 may be referred to as a third transistor.The compensation transistor T3 is configured with a 3-1 transistor T3-1and a 3-2 transistor T3-2 that are adjacent to each other and arecoupled in series. The gate electrodes of the two transistors T3-1 andT3-2 may be part of the scan line 151 or a portion protruding upwardfrom the scan line 151. The above-noted structure may be referred to asa dual gate structure, and it may function to block generation of aleakage current or reduce the same. A portion for connecting twotransistors T3-1 and T3-2 on the semiconductor layer 130 is referred toas a connection portion N3.

A first electrode (not shown) of the 3-1 transistor T3-1 is connected toa second electrode (not shown) of the 3-2 transistor T3-2 at theconnection portion N3. In the case of describing the compensationtransistor T3 as a single transistor, the first electrode (not shown) ofthe 3-2 transistor T3-2 becomes a first electrode S3 of the compensationtransistor T3, and the second electrode (not shown) of the 3-1transistor T3-1 becomes a second electrode D3 of the compensationtransistor T3.

When the configuration in which two transistors are connected in seriesis described as a single compensation transistor T3, the first electrodeS3 of the compensation transistor T3 may be connected to the firstelectrode S6 of the emission control transistor T6 and the secondelectrode D1 of the driving transistor T1. The second electrode D3 ofthe compensation transistor T3 is connected to the first data connectingmember 71 through an opening 63.

The initialization transistor T4 may be referred to as a fourthtransistor.

The initialization transistor T4 is configured with two initializationtransistors, and the two initialization transistors are disposed on aportion where the previous scan line 152 meets the semiconductor layer130. The gate electrode of the initialization transistor T4 may be partof the previous scan line 152. The first electrode S4 of oneinitialization transistor T4 is connected to the second electrode D4 ofanother initialization transistor T4. This may be referred to as a dualgate structure, and it may block the leakage current or reduce the same.

A first end of a second data connecting member 72 is connected to afirst electrode S4 of the initialization transistor T4 through anopening 65, and a second end of the second data connecting member 72 isconnected to the first initialization voltage line 127 through anopening 64 to receive an initialization voltage Vint. The first dataconnecting member 71 is connected to the second electrode D4 of theinitialization transistor T4 through the opening 63.

As described above, by the dual gate structure with the compensationtransistor T3 and the initialization transistor T4, an electron movingpath of the channel is blocked in an off state, and generation of theleakage current may be efficiently prevented.

An exemplary embodiment of the OLED display includes a shield layer M.

Referring to FIG. 1 , a first pixel P1 and a second pixel P2 providednear the same in a first direction are shown. The data line 171 of thesecond pixel P2 transmits the data signal Dm to the pixels that areadjacent to each other upward and downward in a second direction inaddition to the second pixel P2. In this instance, the transmitted datasignal Dm may become different according to luminance realized by therespective pixels, and the data line 171 of the second pixel P2transmits different voltages depending on timing of the compensationtransistor T3 of the first pixel P1.

Further, a parasitic capacitor exists between the compensationtransistor T3 and the data line 171. When a voltage applied to theparasitic capacitor changes as the voltage transmitted by the data line171 changes, a channel potential of the compensation transistor T3changes, so a kickback voltage is generated and becomes unstable.Accordingly, the defect of deteriorating displaying quality is generatedin the display device in which the first electrode S3 of thecompensation transistor T3 is connected to the second electrode D1 ofthe driving transistor T1, and whose luminance is determined by thedriving transistor T1 connected to the OLED.

To prevent this problem, the shield layer M is provided on a top of theconnection portion N3 of the compensation transistor T3 and is alsoprovided between the two adjacent pixels P1 and P2, so the connectionportion N3 is prevented from being influenced by transmission ofdifferent signals of the data line 171 of the second pixel P2, anddisplaying quality may be improved.

However, as the shield layer M is provided between two adjacent pixelsP1 and

P2, it partly overlaps the switching transistor T2, and particularly itmay overlap the first electrode S2 of the switching transistor T2. Thefirst electrode S2 is connected to the data line 171 through the opening62, so a parasitic capacitance is additionally provided between theshield layer M and the data line 171.

Regarding an exemplary embodiment of the OLED display, the shield layerM is provided to overlap at least a part of the compensation transistorT3 and not overlap the switching transistor T2. In detail, the shieldlayer M overlaps the connection portion N3 for connecting the 3-1transistor T3-1 and the 3-2 transistor T3-2 of the compensationtransistor T3. The shield layer M, while not overlapping the switchingtransistor T2, may be provided between a bypass transistor T7 to bedescribed and the data line 171 of the second pixel P2 adjacent in thefirst direction with the first pixel P1 on which the connection portionN3 is provided. In this instance, the shield layer M may overlap atleast a part of the bypass transistor T7.

As described, the parasitic capacitance provided between the shieldlayer M and the switching transistor T2 may be removed by allowing thearea where the shield layer M overlaps the switching transistor T2 to bezero. The first electrode S2 of the switching transistor T2 is connectedto the data line 171 through the opening 62 as described above, so theparasitic capacitance generated by the data line 171 may be reduced.

An RC delay for causing a time delay in the display device is determinedby resistance (“R”) and capacitance (“C”) of the display device. Asdescribed, as the parasitic capacitance reduces, the RC delay of thedata line 171 reduces to decrease the RC delay of the display device,and power consumption of the display device may be resultantly improved,which will be described with reference to FIG. 2 .

The first conductive layer includes the scan line 151, the previous scanline 152, the emission control line 153, and the gate electrode 155, andit may be a gate conductive layer. The second conductive layer includesa storage line 124, the first initialization voltage line 127, thesecond initialization voltage line 128, and a shield layer M. That is,the shield layer M is disposed in a same layer as a second conductivelayer including the extended portion of the storage line 124 and theinitialization voltage lines 127 and 128, and it is disposed on thesemiconductor layer 130 and the first conductive layer.

The shield layer M is electrically connected to the lower voltagesupplying line 172 through the opening Cl formed in a first interlayerinsulating layer (161, refer to FIG. 3 ) to receive a driving voltageELVDD, so it may receive a constant voltage. As described, the shieldlayer M receives the driving voltage ELVDD, so it may be stabilized forthe compensation transistor T3 to be influenced by the differentvoltages transmitted through the data line 171.

Further, in an exemplary embodiment, the parasitic capacitance betweenthe shield layer M and the data line 171 may be reduced by forming theshield layer M so as not to overlap with the switching transistor T2.Accordingly, the kickback voltage due to the parasitic capacitance isreduced and the defects such as image shaking or afterimages arereduced, and therefore, the displaying quality may be improved.

The shield layer M does not overlap the gate electrodes of thecompensation transistors T3-1 and T3-2. In detail, the portionprotruding upward from the scan line 151 overlaps the channel region ofthe 3-1 transistor T3-1 of the semiconductor layer 130 to form a gateelectrode of the 3-1 transistor T3-1. Further, part of the extendedportion of the scan line 151 in the first direction overlaps the channelregion of the 3-2 transistor T3-2 of the semiconductor layer 130 to forma gate electrode of the 3-2 transistor T3-2. In other words, the shieldlayer M does not overlap the scan line 151 on which the gate electrodeof the compensation transistor T3 is disposed. Further, the shield layerM does not overlap the scan line 151, the previous scan line 152, theemission control line 153, and the gate electrode 155. That is, theshield layer M does not overlap the first conductive layer. In otherwords, the shield layer M is provided to be separated from the adjacentfirst conductive layer by a minimum distance, which will be describedwith reference to FIG. 2 .

The insulating layer disposed between the first conductive layer and thesecond conductive layer is thin, so when the two layers overlap eachother in a plan view, they may be shorted and a product characteristicmay be deteriorated. Further, as the shield layer M approaches theportion protruding upward at the scan line 151, that is, the gateelectrode of the 3-1 transistor T3-1, it also approaches an opening 67for connecting the bypass transistor T7 to another layer. Accordingly,interference with other wires may be generated in the process forforming the opening 67, and the quality of the display device may bedeteriorated. Therefore, the shield layer M disposed on the secondconductive layer is provided not to overlap the first conductive layer.

The operation control transistor T5 may be referred to as a fifthtransistor hereinafter.

The gate electrode of the operation control transistor T5 may be part ofthe emission control line 153. The lower voltage supplying line 172 isconnected to the first electrode S5 of the operation control transistorT5 through an opening 68, and the second electrode D5 is connected tothe first electrode S1 of the driving transistor T1 through thesemiconductor layer 130.

The emission control transistor T6 may be referred to as a sixthtransistor hereinafter.

The gate electrode of the emission control transistor T6 may be part ofthe emission control line 153. A fourth data connecting member 74 isconnected to the second electrode D6 of the emission control transistorT6 through an opening 60, and the first electrode S6 is connected to thesecond electrode D1 of the driving transistor through the semiconductorlayer 130. The fourth data connecting member 74, to be described later,may be provided in a same layer as the data line 171 or the lowervoltage supplying line 172, and it is electrically connected to anauxiliary connecting member 179 to be described, and is resultantlyconnected to a pixel electrode (not shown) of the OLED.

The bypass transistor T7 may be referred to as a seventh transistorhereinafter.

A gate electrode G7 of the bypass transistor T7 may be part of theprevious scan line 152. A first end of a third data connecting member 73is connected to the second electrode D7 of the bypass transistor T7through the opening 67, and a second end of the third data connectingmember 73 is connected to the second initialization voltage line 128through an opening 66 to receive an initialization voltage Vint. Thefirst electrode S7 of the bypass transistor T7 is connected to thesecond electrode D6 of the emission control transistor T6.

The storage capacitor Cst includes the gate electrode 155 and anextended portion of the storage line 124 overlapping each other with thesecond gate insulating layer 142 (refer to FIG. 3 ) therebetween. Thegate electrode 155 corresponds to a first storage electrode of thestorage capacitor Cst, and the extended portion of the storage line 124corresponds to the second storage electrode. Here, the second gateinsulating layer 142 (refer to FIG. 3 ) provided between the gateelectrode 155 and the storage line 124 becomes a dielectric material,and capacitance is determined by charges stored in the storage capacitorCst and a voltage between the first and second storage electrodes. Bythe gate electrode 155 as a first storage electrode, the space forforming a storage capacitor Cst in the space narrowed by the channel ofthe driving transistor T1 occupying a large area in the pixel may beobtained.

The lower voltage supplying line 172 is connected to the extendedportion of the storage line 124 through an opening 69. Hence, thestorage capacitor Cst stores charges corresponding to a differencebetween the driving voltage ELVDD transmitted to the extended portion ofthe storage line 124 through the lower voltage supplying line 172 andthe gate voltage of the gate electrode 155.

Regarding the first data layer, as described above, the plurality ofdata connecting members 71, 72, 73, and 74 may include the data line 171and the lower voltage supplying line 172, and they may be disposed in asame layer with a same material.

A first end of the first data connecting member 71 is connected to thesecond electrode D3 of the compensation transistor T3 through theopening 63, and a second end thereof is connected to the gate electrode155 through the opening 61 formed in the opening 56 formed in theextended portion of the storage line 124.

A first end of the second data connecting member 72 is connected to thefirst initialization voltage line 127 through the opening 64, and asecond end thereof is connected to the first electrode S4 of theinitialization transistor T4 through the opening 65.

A first end of the third data connecting member 73 is connected to thesecond initialization voltage line 128 through the opening 66, and asecond end thereof is connected to the second electrode D7 of the bypasstransistor T7 through the opening 67.

The fourth data connecting member 74 is connected to the secondelectrode D6 of the emission control transistor T6 through the opening60. The fourth data connecting member 74 is electrically connected tothe auxiliary connecting member 179 to be described, and is resultantlyelectrically connected to the pixel electrode (not shown) of the OLED.

As described, the data line 171, the lower voltage supplying line 172and the plurality of data connecting members 71, 72, 73, and 74 may bedisposed in a same layer, and in detail, they may be disposed on thefirst interlayer insulating layer 161 (refer to FIG. 3 ). In thisinstance, the lower voltage supplying line 172 supplies a constantelectrical signal to a plurality of pixels, and so as to realize ahigh-quality display device, it is needed to prevent a voltage changesuch as a voltage drop. However, as shown in FIG. 1 , the lower voltagesupplying line 172 is provided in a same layer as the data line 171 andthe plurality of connecting members 71, 72, 73, and 74, so it isdifficult to acquire its area.

Therefore, a second data layer including an upper voltage supplying line178 is provided on the first data layer. The second data layer mayinclude the upper voltage supplying line 178 and the auxiliaryconnecting member 179.

The upper voltage supplying line 178 is electrically connected to thelower voltage supplying line 172 through an opening 81, thereby solvingthe voltage drop problem on the lower voltage supplying line 172. Theupper voltage supplying line 178 may have a connected lattice shape in aplurality of pixel areas, and its detailed shape may be variable.

The auxiliary connecting member 179 is provided in a same layer as theupper voltage supplying line 178. As described above, the firstelectrode S7 of the bypass transistor T7 must be electrically connectedto the pixel electrode (not shown) of the OLED. Therefore, the auxiliaryconnecting member 179 may be connected through an opening 83 to thefourth data connecting member 74 connected to the first electrode S7 ofthe bypass transistor T7 through the opening 60. The auxiliaryconnecting member 179 may be connected to a pixel electrode (not shown)through an opening 85 formed at the top of the auxiliary connectingmember 179.

The OLED includes a pixel electrode (not shown) connected through theopening 85, an organic emission layer (not shown), and a commonelectrode (not shown).

An exemplary embodiment of disposal of a shield layer of an OLED displaywill now be described with reference to FIG. 2 . FIG. 2 shows anenlarged view of part of a pixel shown in FIG. 1 . In FIG. 2 , the sameconfigurations as those described with reference to FIG. 1 will use thesame reference numerals, and the same contents as those described withreference to FIG. 1 will be omitted.

Referring to FIG. 2 , the shield layer M includes an overlapping portionM1 for overlapping the connection portion N3, an extended portion M2 forextending from the overlapping portion M1, and an expanded portion M3for expanding from the extended portion M2. The shield layer M may beprovided to traverse a first pixel P1 and a second pixel P2 providednear the first pixel P1 in the first direction.

The overlapping portion M1 will now be described. The overlappingportion M1 does not overlap the scan line 151. That is, the shield layerM is separated from the scan line 151 with a constant gap therebetween.As described with reference to FIG. 1 , a connection portion N3 isprovided at a portion where 3-1 and 3-2 transistors T3-1 and T3-2 areconnected. When a minimum distance between the overlapping portion M1and a portion protruding upward from the scan line 151 is set to be afirst gap d1, the first gap dl may be about 1.2 micrometers (μm) toabout 1.5 μm, and it may be about 1.2 μm, for example.

The overlapping portion M1 does not overlap the data line 171 of thesecond pixel P2 provided on a right side thereof. This is to minimizeparasitic capacitance of the data line 171. Further, the overlappingportion M1 may be provided at a top of the connection portion N3 andsubstantially in parallel to the data line 171, and does not overlap theprevious scan line 152.

The overlapping portion M1 overlaps the connection portion N3 and doesnot overlap the switching transistor T2, particularly the firstelectrode S2. When the shield layer M overlaps the switching transistorT2, the first electrode S2 of the switching transistor T2 is connectedto the data line 171 through the opening 62, so the parasiticcapacitance between the shield layer M and the data line 171 increases.Therefore, to prevent the generation of parasitic capacitance, in anexemplary embodiment, the shield layer M does not overlap the switchingtransistor T2 and is provided between the switching transistor T2 andthe bypass transistor T7.

The shield layer M is shown that it does not overlap the bypasstransistor T7 in FIG. 2 , and it may overlap at least a part of thebypass transistor T7 in exemplary embodiments.

A width of the overlapping portion M1 is changeable by a portion wherethe same overlaps the connection portion N3 and a portion where the samedoes not overlap it, and the width may be larger at the portion wherethe same overlaps the connection portion N3.

The extended portion M2 extends in parallel to the previous scan line152 toward the second pixel P2 from the overlapping portion M1. That is,the extended portion M2 may be disposed to traverse two adjacent pixels.The extended portion M2 is provided not to overlap the switchingtransistor T2, particularly the first electrode S2 according to thereason described with reference to the overlapping portion M1, therebyminimizing the parasitic capacitance of the data line 171.

The extended portion M2 does not overlap the previous scan line 152, anda second gap d2 between the extended portion M2 and the previous scanline 152 may be about 1.2 μm to about 1.5 μm, and it may be about 1.2μm, for example.

The expanded portion M3 may be expanded along the semiconductor layer130 extending below the second electrode D4 of the initializationtransistor T4 from the extended portion M2. The expanded portion M3 isexpanded only until it does not overlap the scan line 151. Although thedistance between the expanded portion M3 and the scan line 151 is notshown, but it may be about 1.2 μm to about 1.5 μm, and about 1.2 μm, forexample, in a like manner of the above-noted first gap d1 and the secondgap d2.

The expanded portion M3 may overlap the initialization transistor T4 ofthe second pixel P2, particularly the second electrode D4. Further, theexpanded portion M3 may receive the driving voltage ELVDD through theopening C1 formed in the first interlayer insulating layer 161 (refer toFIG. 3 ) provided on the expanded portion M3.

The expanded portion M3 does not overlap the switching transistor T2 tothus minimize the parasitic capacitance of the data line 171. Further,the width of the expanded portion M3 may vary according to a curvedshape of the semiconductor layer 130 configuring the initializationtransistor T4.

The overlapping portion M1, the extended portion M2, and the expandedportion M3 of the shield layer M may have different widths from oneanother.

A minimum width of the shield layer M is not limited by a specificnumber value, but it may be about 2.5 μm to about 3.3 μm, and it may beabout 3.0 μm, for example. The minimum width of the shield layer M isshown in FIG. 2 to be a third gap d3 that is the width of the extendedportion M2, which is only an example, and the minimum width of theshield layer M may be the width of the overlapping portion M1 or theexpanded portion M3 instead of the extended portion M2.

The parasitic capacitance of the data line 171 may be minimized byminimizing the overlapping width of the shield layer M and the switchingtransistor T2 electrically connected to the data line 171. Accordingly,the RC delay of the data line 171 is reduced, and the RC delay of thedisplay device is reduced, thereby improving display quality such asshaking of image displaying or afterimages.

In an exemplary embodiment, the shield layer M is disposed not tooverlap the switching transistor T2, so the parasitic capacitance of thedata line 171 may be reduced with a ratio of about 15% to about 20%,particularly a ratio of about 17%.

A stacked structure of an exemplary embodiment of an OLED display willnow be described with reference to FIG. 3 . FIG. 3 shows across-sectional view taken along line of FIG. 2 .

In FIG. 3 , the same configurations as those described in an exemplaryembodiment will use the same reference numerals, and the same contentsas those described in an exemplary embodiment will be omitted.

Referring to FIGS. 1, 2 and 3 , an exemplary embodiment of the OLEDdisplay includes a substrate 110. The substrate 110 may include variousmaterials such as glass, metal, or plastic. A barrier layer 111 isprovided on the substrate 110. The barrier layer 111 may include aninorganic insulating material such as a silicon oxide, a siliconnitride, or an aluminum oxide, or it may include an organic insulatingmaterial such as polyimide acryl. The barrier layer 111 may prevent animpurity from being input to the transistor and may flatten one side ofthe substrate 110. The barrier layer 111 may be omitted in otherexemplary embodiments.

The semiconductor layer 130 of the plurality of transistors T1, T2, T3,T4, T5, T6, and T7 is provided on the barrier layer 111. Thesemiconductor layer 130 includes first electrodes S1 to S7 and secondelectrodes D1 to D7 of the respective transistors. Detailed contentshave been described so they will be omitted. In FIG. 3 , thesemiconductor layer 130 of the switching transistor T2, the compensationtransistor T3, and the initialization transistor T4 is shown, andparticularly, the first electrode S2 of the switching transistor T2, theconnection portion N3 of the compensation transistor T3, and the secondelectrode D4 of the initialization transistor T4 are shown.

A first gate insulating layer 141 for covering the semiconductor layer130 is provided on the semiconductor layer 130.

A first conductive layer is provided on the first gate insulating layer141. The first conductive layer may include gate electrodes (includingthe gate electrode 155) of the plurality of transistors T1, T2, T3, T4,T5, T6, and T7, the scan line 151, the previous scan line 152, and theemission control line 153.

The second gate insulating layer 142 for covering the first conductivelayer is provided on the first conductive layer. In an exemplaryembodiment, the first gate insulating layer 141 and the second gateinsulating layer 142 may include a material such as a silicon nitride, asilicon oxide, or an aluminum oxide.

A second conductive layer is provided on the second gate insulatinglayer 142. The second conductive layer includes the storage line 124,the first initialization voltage line 127, the second initializationvoltage line 128, and the shield layer M, but the invention is notlimited thereto.

The shield layer M is provided between the compensation transistor T3and the data line 171 in a cross-sectional view, and it overlaps atleast a part of the compensation transistor T3. Here, the compensationtransistor T3 is provided at the bottom of the shield layer M, and thedata line 171 is provided on the first data layer provided at the top ofthe shield layer M. Therefore, the shield layer M may prevent theadditional generation of parasitic capacitance between the data line 171and the compensation transistor T3, particularly the connection portionN3.

Further, the shield layer M does not overlap the switching transistorT2, particularly the first electrode S2. The switching transistor T2 iselectrically connected to the data line 171 for supplying a data signalDm through the opening 62 formed in the first gate insulating layer 141,the second gate insulating layer 142, and the first interlayerinsulating layer 161. The shield layer M is provided not to overlap theswitching transistor T2, thereby eliminating the parasitic capacitancebetween the shield layer M and the data line 171.

In addition, the shield layer M may overlap the initializationtransistor T4, particularly the second electrode D4. In this instance,the shield layer M is connected to the lower voltage supplying line 172through the opening C1 formed in the first interlayer insulating layer161, and receives the driving voltage ELVDD. Accordingly, a constantvoltage is applied to the shield layer M to prevent the change ofvoltage, reduce the kickback voltage that causes image defects, andthereby improve the displaying quality.

The first interlayer insulating layer 161 for covering the secondconductive layer is provided on the second conductive layer. In anexemplary embodiment, the first interlayer insulating layer 161 mayinclude a material such as a silicon nitride, a silicon oxide, or analuminum oxide, and it may include an organic insulating material.

The first data layer is provided on the first interlayer insulatinglayer 161. The first data layer may include the data line 171, the lowervoltage supplying line 172, the first data connecting member 71, thesecond data connecting member 72, the third data connecting member 73,and the fourth data connecting member 74. The first data layer may beelectrically connected to the semiconductor layer 130 provided at thebottom through the openings 60, 61, 62, 63, 64, 65, 66, 67, 68, and 69formed in at least a part of the first gate insulating layer 141, thesecond gate insulating layer 142, and the first interlayer insulatinglayer 161.

The first data layer may become first electrodes S1, S2, S3, S4, S5, S6,and S7 and second electrodes D1, D2, D3, D4, D5, D6, and D7 connected tothe first region and the second region of the semiconductor layer 130.When one of the first electrodes S1, S2, S3, S4, S5, S6, and S7 and thesecond electrodes D1, D2, D3, D4, D5, D6, and D7 is a source electrode,the other may be a drain electrode. In detail, in FIG. 3 , the data line171 is electrically connected to the first electrode S2 of the switchingtransistor T2 provided at the bottom through the opening 62 formed inthe first gate insulating layer 141, the second gate insulating layer142, and the first interlayer insulating layer 161. The lower voltagesupplying line 172 is connected to the shield layer M, particularly theexpanded portion M3, through the opening C1 formed in the firstinterlayer insulating layer 161.

A second interlayer insulating layer 162 is provided on the first datalayer. In an exemplary embodiment, the second interlayer insulatinglayer 162 may include a material such as a silicon nitride, a siliconoxide, or an aluminum oxide, and it may include an organic insulatingmaterial.

A second data layer is provided on the second interlayer insulatinglayer 162. The second data layer may include the upper voltage supplyingline 178 and the auxiliary connecting member 179. Although not shown inFIG. 3 , the second data layer may be, as described with reference toFIG. 1 , electrically connected to the first data layer provided at thebottom through the openings 81 and 83 formed in the second interlayerinsulating layer 162.

In detail, the upper voltage supplying line 178 may be connected to thelower voltage supplying line 172 through the opening 81 formed in thesecond interlayer insulating layer 162 to prevent the voltage drop ofthe lower voltage supplying line 172. The auxiliary connecting member179 may be connected to the fourth data connecting member 74 through theopening 83 formed in the second interlayer insulating layer 162. Asdescribed with reference to FIG. 1 , the fourth data connecting member74 may be connected to the semiconductor layer 130 provided at thebottom, particularly the second electrode D6 of the emission controltransistor T6 through the opening 60 formed in at least a part of thefirst gate insulating layer 141, the second gate insulating layer 142,and the first interlayer insulating layer 161. Therefore, the auxiliaryconnecting member 179 may be connected to the semiconductor layer 130 atthe bottom, particularly the second electrode D6 of the emission controltransistor T6. A passivation layer 180 for covering the same isprovided. The passivation layer 180 that is also referred to as aplanarization film may include an organic insulating material.

A pixel electrode (not shown) is provided on the passivation layer 180.The pixel electrode is connected to the auxiliary connecting member 179through the opening 85 (refer to FIG. 1 ) formed in the passivationlayer 180. A partition wall (not shown) is provided on the passivationlayer 180 and the pixel electrode. An open portion overlapping the pixelelectrode is defined in the partition wall, and an organic emissionlayer is provided on the open portion. A common electrode (not shown) isprovided on the organic emission layer and the partition wall. The pixelelectrode, the organic emission layer, and the common electrodeconfigure an OLED.

In exemplary embodiments, the pixel electrode may be an anode that is ahole injection electrode, and the common electrode may be a cathode thatis an electron injection electrode. On the contrary, in other exemplaryembodiments, the pixel electrode may be a cathode, and the commonelectrode may be an anode. When holes and electrons are injected intothe organic emission layer from the pixel electrode and the commonelectrode, excitons that are a combination of the injected holes andelectrons transit to the ground state from the excited state.

An exemplary embodiment of an OLED display will now be described withreference to FIGS. 4 and 5 .

FIG. 4 shows an equivalent circuit diagram of an exemplary embodiment ofa pixel of an OLED display, and FIG. 5 shows an exemplary embodiment ofa timing diagram of signals applied to a pixel of an OLED display.Hereinafter, the same configurations as those described in an exemplaryembodiment will use the same reference numerals, and the same contentsas those described in an exemplary embodiment will be omitted.

Referring to FIG. 4 , an exemplary embodiment of one pixel of an OLEDdisplay includes a plurality of signal lines 151, 152, 153, 158, 127,128, and 171, a plurality of transistors T1, T2, T3 (refer to FIGS. 3 ),T4, T5, T6, and T7 connected to the plurality of signal lines, a storagecapacitor Cst, voltage supplying lines 172 and 178, and an OLED.

The plurality of signal lines apply a scan signal Sn, a previous scansignal Sn-1, a bypass signal GB, an emission control signal EM, and aninitialization voltage Vint, respectively, and include a scan line 151,a previous scan line 152, an emission control line 153, a bypass controlline 158, and initialization voltage lines 127 and 128 disposed in a rowdirection. They may include a data line 171 and voltage supplying lines172 and 178 traversing the scan line 151, the previous scan line 152,the emission control line 153, the bypass control line 158, and theinitialization voltage lines 127 and 128, and applying a data signal Dmand a driving voltage ELVDD to the pixels.

The scan line 151 is connected to a gate driver (not shown) to transmita scan signal Sn to the switching transistor T2 and the third transistorT3. The previous scan line 152 is connected to the gate driver totransmit a previous scan signal Sn-1 applied to the pixel provided at aprevious position to the fourth transistor T4. The fourth transistor T4includes two transistors connected in series, so the previous scansignal Sn-1 is applied to the gate electrodes of the two transistorsconnected in series and included in the fourth transistor T4.

The emission control line 153 is connected to an emission controller(not shown), and it transmits an emission control signal EM forcontrolling a time when an OLED emits light to the fifth transistor T5and the sixth transistor T6. The bypass control line 158 transmits thebypass signal GB to the seventh transistor T7, and in some exemplaryembodiments, may transmit a same signal as the previous scan signal Sn-1or the scan signal Sn thereto.

The data line 171 transmits the data signal Dm generated by a datadriver (not shown), and luminance of the light emitted by the OLEDchanges according to the data signal Dm. The lower voltage supplyingline 172 applies the driving voltage ELVDD. The first initializationvoltage line 127 transmits the initialization voltage Vint forinitializing the driving transistor T1, and second initializationvoltage line 128 transmits the initialization voltage Vint forinitializing the anode of the OLED. A common voltage line 741 appliesthe common voltage ELVSS. The voltages applied to the lower voltagesupplying line 172, the initialization voltage lines 127 and 128, andthe common voltage line 741 may respectively be a constant voltage.

The plurality of transistors may include a driving transistor T1, aswitching transistor T2, a compensation transistor T3, an initializationtransistor T4, an operation control transistor T5, an emission controltransistor T6, and a bypass transistor T7.

The plurality of transistors T1, T2, T3, T4, T5, T6, and T7 will now bedescribed.

First, the driving transistor T1 controls a current output according tothe applied data signal Dm, the output driving current Id is applied tothe OLED, and brightness of the OLED is controlled by the data signalDm. For this purpose, the first electrode S1 of the driving transistorT1 is disposed to receive the driving voltage ELVDD, and it is connectedto the lower voltage supplying line 172 through the operation controltransistor T5. Further, the first electrode S1 of the driving transistorT1 is connected to the second electrode D2 of the switching transistorT2 to receive the data signal Dm. The second electrode D1 (i.e., anelectrode on the output side) is disposed to output a current to theOLED, and is connected to the anode of the OLED through the emissioncontrol transistor T6.

The gate electrode G1 is connected to one electrode (the first storageelectrode E1 of the storage capacitor Cst. The voltage at the gateelectrode G1 changes according to the voltage stored in the storagecapacitor Cst, and the driving current Id output by the drivingtransistor T1 changes. The storage capacitor Cst maintains the voltageapplied to the gate electrode G1 of the driving transistor T1.

The switching transistor T2 receives the data signal Dm into the pixel.The gate electrode G2 is connected to the scan line 151, and the firstelectrode S2 is connected to the data line 171. The second electrode D2of the switching transistor T2 is connected to the first electrode S1 ofthe driving transistor T1. When the switching transistor T2 is turned onaccording to the scan signal Sn transmitted through the scan line 151,the data signal Dm transmitted through the data line 171 is transmittedto the first electrode S1 of the driving transistor T1.

The compensation transistor T3 and the initialization transistor T4 areshown with a configuration to include two transistors connected inseries. Here, the configuration of connection in series represents aconfiguration in which gate electrodes of two transistors T3-1 and T3-2are connected to receive the same signal, and an output of onetransistor is applied to the input of the other transistor.

The compensation transistor T3 has a configuration in which the 3-1 and3-2 transistors T3-1 and T3-2 are connected in series. The gateelectrode G3-1 of the 3-1 transistor T3-1 and the gate electrode G3-2 ofthe 3-2 transistor T3-2 are connected to each other.

The compensation transistor T3 transmits a compensation voltage (thevoltage of Dm +Vth) that is changed when the data signal Dm passesthrough the driving transistor T1 to the first storage electrode E1 ofthe storage capacitor Cst. The compensation transistor T3 includes the3-1 transistor T3-1 and the 3-2 transistor T3-2 connected in series. Thegate electrodes G3-1 and G3-2 of the two transistors T3-1 and T3-2 areconnected to the scan line 151. The first electrode S3-2 of the 3-2transistor T3-2 is connected to the second electrode D1 of the drivingtransistor T1, and the second electrode D3-1 of the 3-1 transistor T3-1is connected to the first storage electrode E1 of the storage capacitorCst and the gate electrode G1 of the driving transistor T1.

Further, the first electrode S3-1 of the 3-1 transistor T3-1 and thesecond electrode D3-2 of the 3-2 transistor T3-2 are connected to eachother at the connection portion N3. The connection portion N3 may be aconnection node where the two transistors T3-1 and T3-2 are connected toeach other.

In the case of describing the compensation transistor T3 as a singletransistor, the first electrode S3-2 of the 3-2 transistor T3-2 becomesthe first electrode S3 of the compensation transistor T3, and the secondelectrode D3-1 of the 3-1 transistor T3-1 becomes the second electrodeD3 of the compensation transistor T3. The compensation transistor T3 isturned on by the scan signal Sn received through the scan line 151 toconnect the gate electrode G1 of the driving transistor T1 and thesecond electrode D1, and to also connect the second electrode D1 of thedriving transistor T1 and the first storage electrode El of the storagecapacitor Cst. In this instance, parasitic capacitance Cp is generatedbetween part of the compensation transistor T3 and the data line 171.

An exemplary embodiment of the OLED display further includes a shieldlayer M. The shield layer M overlaps the connection portion N3 forconnecting the compensation transistor T3, particularly the 3-1transistor T3-1 and the 3-2 transistor T3-2. The first electrode S2 ofthe switching transistor T2 receives a data signal Dm from the data line171. The shield layer M is provided not to overlap the switchingtransistor T2, thereby eliminating the parasitic capacitance between theshield layer M and the data line 171. Hence, capacitance of theparasitic capacitor Cp of the data line 171 may be reduced, the RC delayof the data line 171 is reduced, and power consumption of the displaydevice may be resultantly improved.

The initialization transistor T4 initializes the gate electrode G1 ofthe driving transistor T1 and the first storage electrode E1 of thestorage capacitor Cst. The gate electrode G4 is connected to theprevious scan line 152, and the first electrode S4 is connected to thefirst initialization voltage line 127. The second electrode D4 of theinitialization transistor T4 is connected to the first storage electrodeE1 of the storage capacitor Cst and the gate electrode G1 of the drivingtransistor T1 through the second electrode D3 of the compensationtransistor T3.

The initialization transistor T4 transmits the initialization voltageVint to the gate electrode G1 of the driving transistor T1 and the firststorage electrode E1 of the storage capacitor Cst according to theprevious scan signal Sn-1 received through the previous scan line 152.Accordingly, the gate voltage of the gate electrode G1 of the drivingtransistor T1 and the storage capacitor Cst are initialized. Theinitialization voltage Vint may be a voltage having a low value andturning on the driving transistor T1.

The initialization transistor T4 has a configuration including twotransistors connected in series. The initialization transistor T4 isconnected in series, and it may be provided with a single transistor inexemplary embodiments.

The operation control transistor T5 transmits the driving voltage ELVDDto the driving transistor T1. The gate electrode G5 is connected to theemission control line 153, and the first electrode S5 is connected tothe lower voltage supplying line 172. The second electrode D5 of theoperation control transistor T5 is connected to the first electrode S1of the driving transistor T1.

The emission control transistor T6 transmits the driving current Idoutput by the driving transistor T1 to the OLED. The gate electrode G6is connected to the emission control line 153, and the first electrodeS6 is connected to the second electrode D1 of the driving transistor T1.The second electrode D6 of the emission control transistor T6 isconnected to the anode of the OLED.

The operation control transistor T5 and the emission control transistorT6 are simultaneously turned on according to the emission control signalEM received through the emission control line 153, and when the drivingvoltage ELVDD is applied to the first electrode Si of the drivingtransistor T1 through the operation control transistor T5, the drivingtransistor T1 outputs the driving current Id according to the voltage ofthe gate electrode G1 of the driving transistor T1 (i.e., the voltage ofthe first storage electrode E1 of the storage capacitor Cst). The outputdriving current Id is transmitted to the OLED through the emissioncontrol transistor T6. As the current Ioled flows to the OLED, the OLEDemits light.

The bypass transistor T7 initializes the anode of the OLED. The gateelectrode G7 is connected to the bypass control line 158, the firstelectrode S7 is connected to the anode of the OLED, and the secondelectrode D7 is connected to the second initialization voltage line 128.In exemplary embodiments, when the bypass control line 158 is connectedto the previous scan line 152, the bypass signal GB may be a signal withthe same timing as the previous scan signal Sn-1, and when the bypasscontrol line 158 is connected to the scan line 151, the bypass signal GBmay be a signal with the same timing as the scan signal Sn. When thebypass transistor T7 is turned on by the bypass signal GB, theinitialization voltage Vint is applied to the anode of the OLED to beinitialized.

The first storage electrode E1 of the storage capacitor Cst is connectedto the gate electrode G1 of the driving transistor T1, the secondelectrode D3 of the compensation transistor T3, and the second electrodeD4 of the initialization transistor T4, and the second storage electrodeE2 is connected to the lower voltage supplying line 172. As a result,the first storage electrode E1 determines the voltage at the gateelectrode G1 of the driving transistor T1. And the first storageelectrode E1 receives the data signal Dm through the second electrode D3of the compensation transistor T3, and receives the initializationvoltage Vint through the second electrode D4 of the initializationtransistor T4.

A circuit of one pixel in an exemplary embodiment includes seventransistors T1 to T7 and one capacitor Cst, but the invention is notlimited thereto, and the number of transistors and capacitors and theircombinations are modifiable in various ways.

Although not shown, the OLED display includes a display area fordisplaying an image, and the pixels are arranged in the display area invarious ways such as in a matrix form.

An exemplary embodiment of an operation of one pixel of an OLED displaywill now be described with reference to FIG. 5 .

Referring to FIG. 5 , a low-level previous scan signal Sn-1 is suppliedto the pixel through the previous scan line 152 during an initializationsection. Upon receiving the same, the initialization transistor T4 isturned on such that the initialization voltage Vint is applied to thegate electrode G1 of the driving transistor T1 and the first storageelectrode E1 of the storage capacitor Cst through the initializationtransistor T4. As a result, the driving transistor T1 and the storagecapacitor Cst are initialized. The voltage of the initialization voltageVint may be a low voltage, and the driving transistor T1 may be turnedon.

The bypass transistor T7 in the initialization section may initializethe anode of the OLED, and may prevent the small amount of currentdischarged in the condition that the driving transistor T1 is not turnedon from being applied to the OLED. Here, the small amount of current isa bypass current Ibp (refer to FIG. 4 ), and is discharged to theinitialization voltage Vint end through the bypass transistor T7. As aresult, the OLED does not discharge unneeded light so that the blackgray may be displayed more clearly and the contrast ratio may beimproved. In this case, the bypass signal GB may be a signal with thesame timing as the scan signal Sn, and in an exemplary embodiment, itmay be a signal with the same timing as the previous scan signal Sn-1.The bypass transistor T7 may be omitted in other exemplary embodiments.

During a data programming section, a low-level scan signal Sn issupplied to the pixel through the scan line 151. In this instance, thebypass signal GB with the same timing as the scan signal Sn may besupplied. The switching transistor T2 and the compensation transistor T3are turned on by the low-level scan signal Sn.

When the switching transistor T2 is turned on, the data signal Dm isapplied to the first electrode Si of the driving transistor T1 throughthe switching transistor T2.

In this instance, parasitic capacitance may be formed between the dataline 171 for supplying the data signal Dm and the switching transistorT2 or the compensation transistor T3. In an exemplary embodiment of theOLED display, the shield layer M is provided to overlap the compensationtransistor T3, particularly the connection portion N3, to thus reducethe parasitic capacitance caused by the data line 171 and thecompensation transistor T3. Further, the shield layer M is provided notto overlap the switching transistor T2 for receiving the data signal Dmto thereby eliminate the parasitic capacitance caused by the data line171 and the compensation transistor T3.

Accordingly, the parasitic capacitance of the data line 171 may beminimized in the OLED display in an exemplary embodiment, therebyminimizing the RC delay of the data line 171, and finally improving thedisplay quality of the display device while reducing power consumption.

Further, during the data programming section, the compensationtransistor T3 is turned on, and as a result, the second electrode D1 ofthe driving transistor T1 is electrically connected to the gateelectrode G1 and the first storage electrode E1 of the storage capacitorCst. The gate electrode G1 of the driving transistor T1 and the secondelectrode D1 of the driving transistor T1 are diode-connected. Duringthe initialization section, the driving transistor T1 is turned onbecause a low voltage (initialization voltage Vint) is applied to thegate electrode G1. As a result, the data signal Dm input to the firstelectrode S1 of the driving transistor T1 passes through the channel ofthe driving transistor T1, is output by the second electrode D1, passesthrough the compensation transistor T3, and is stored in the firststorage electrode E1 of the storage capacitor Cst.

In this instance, the voltage applied to the first storage electrode E1changes according to the threshold voltage Vth of the driving transistorT1, the voltage at the first electrode S1 of the driving transistor T1is the data signal Dm, and when the voltage at the gate electrode G1 ofthe driving transistor T1 is the initialization voltage Vint, thevoltage output to the second electrode D1 may be Vgs+Vth. Here, asdescribed above, the voltage Vgs is a voltage difference between thegate electrode G1 of the driving transistor T1 and the first electrodeS1, so it may have the value of Dm-Vint. Therefore, the voltage outputby the second electrode D1 and stored in the first storage electrode E1may have the value of Dm-Vint+Vth.

During an emission section, the emission control signal EM supplied bythe emission control line 153 has a low-level value, so the operationcontrol transistor T5 and the emission control transistor T6 are turnedon. As a result, the driving voltage ELVDD is applied to the firstelectrode S1 of the driving transistor T1, and the second electrode D1of the driving transistor T1 is connected to the OLED. The drivingtransistor T1 generates a driving current Id according to the voltagedifference between the voltage at the gate electrode G1 and the voltage(i.e., the driving voltage ELVDD) at the first electrode S1.

Regarding the calculation equations, the value of Vth may be slightlygreater than zero or a negative value in the case of a P-type transistorusing a polycrystalline semiconductor. Further, the expression of + and− is changeable according to the voltage calculating direction. When theemission section is finished, the initialization section is provided torepeat the same operation from the start.

One of the first electrodes and the second electrodes of the pluralityof transistors T1, T2, T3, T4, T5, T6, and T7 may be source electrodesand the other thereof may be drain electrodes according to the voltageor current applying direction.

Further, in exemplary embodiments, during the initialization section,the low-level bypass signal GB may be applied to the bypass transistorT7. Upon receiving the same, the bypass transistor T7 is turned on, sothe initialization voltage Vint is applied to the anode of the OLEDthrough the bypass transistor T7. As a result, the anode of the OLED isinitialized.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. An organic light emitting diode displaycomprising: a substrate including a first pixel and a second pixel; eachof the first pixel and the second pixel comprises: a driving transistorincluding a first gate electrode, a first channel region, a firstelectrode connected to a driving voltage line transmitting a drivingvoltage, and a second electrode, a second transistor including a secondgate electrode, a second channel region, a first electrode connected toa data line, and a second electrode connected to the first electrode ofthe driving transistor, a third transistor including a third gateelectrode, a third channel region, a first electrode connected to thesecond electrode of the driving transistor, and a second electrodeconnected to the first gate electrode of the driving transistor, afourth transistor including a fourth gate electrode, a fourth channelregion, a first electrode connected to the second electrode of the thirdtransistor, and a second electrode connected to an initializationvoltage line, and an organic light emitting diode including an anodeelectrically connected to the second electrode of the drivingtransistor, wherein the third transistor includes a first sub transistorand a second sub transistor connected in series to each other at a firstsemiconductor connection portion disposed in a semiconductor layer, thethird transistor and the fourth transistor are connected to each otherat a second semiconductor connection portion disposed between the thirdchannel region and the fourth channel region in the semiconductor layer,the second transistor and the data line are connected to each other at athird semiconductor connection portion disposed between the secondchannel region and a first contact portion connected to the data line inthe semiconductor layer, the first semiconductor connection portion ofthe first pixel overlaps a first shield pattern, the first shieldpattern overlaps one of the second semiconductor connection portions ofthe first pixel and the second pixel, the first shield pattern does notoverlap the third semiconductor connection portions of the first pixeland the second pixel, and the first shield pattern receives the drivingvoltage.
 2. The organic light emitting diode display of claim 1, furthercomprises: a first conductive layer disposed on the semiconductor layer,a second conductive layer disposed on the first conductive layer, and afirst data layer disposed on the second conductive layer, wherein thefirst conductive layer includes the first gate electrode and the secondgate electrode.
 3. The organic light emitting diode display of claim 2,wherein the second conductive layer includes the first shield pattern.4. The organic light emitting diode display of claim 3, wherein: thefirst data layer includes a voltage line connected to adjacent pixels,and the first shield pattern overlaps the voltage line.
 5. The organiclight emitting diode display of claim 1, wherein: the second gateelectrode of the second transistor is connected to a scan line extendingin a first direction, and the first shield pattern includes an extendingportion and a first portion, the extending portion of the first shieldpattern extends in a substantially same direction as the firstdirection, the first portion of the first shield pattern overlaps thefirst semiconductor connection portion of the first pixel, and the firstportion of the first shield pattern is extended from the extendingportion of the first shield pattern.
 6. The organic light emitting diodedisplay of claim 5, wherein the first pixel and the second pixel isdisposed adjacent in the first direction.
 7. The organic light emittingdiode display of claim 5, wherein: the second semiconductor connectionportion is electrically connected to the first gate electrode of thedriving transistor at a second contact portion, the first shield patternfurther includes a second portion, and the second portion of the firstshield pattern is disposed between the second contact portion and thefirst contact portion in a plan view.
 8. The organic light emittingdiode display of claim 7, wherein the second portion of the first shieldpattern is disposed at an opposite end to the first portion of the firstshield pattern with respect to the extending portion of the first shieldpattern.
 9. The organic light emitting diode display of claim 8, whereinthe first portion and the second portion of first shield pattern isprotruded from a corresponding end of the extending portion of firstshield pattern.
 10. The organic light emitting diode display of claim 9,wherein the first portion and the second portion of first shield patternare protruded in a same direction from the extending portion of firstshield pattern.
 11. The organic light emitting diode display of claim 7,wherein the second portion of the first shield pattern receives thedriving voltage from the driving voltage line.
 12. The organic lightemitting diode display of claim 11, wherein the second portion of thefirst shield pattern overlaps at least a part of the fourth transistor.13. The organic light emitting diode display of claim 2, furthercomprising: a first signal line connected to the second gate electrode,and a second signal line connected to the third gate electrode, whereinthe first conductive layer further includes the first signal line andthe second signal line.
 14. The organic light emitting diode display ofclaim 13, wherein the first signal line is a scan line which transmits ascan signal.
 15. The organic light emitting diode display of claim 14,wherein the second signal line is a previous scan line which transmits aprevious scan signal.
 16. The organic light emitting diode display ofclaim 1, wherein the first semiconductor connection portion is disposedas a bent pattern of the semiconductor layer.
 17. The organic lightemitting diode display of claim 1, wherein the driving voltage line isdisposed in a same layer as the data line.
 18. The organic lightemitting diode display of claim 1, further comprising: an auxiliaryconnecting member disposed in a same layer as the data line, andelectrically connected to the anode of the organic light emitting diode.19. The organic light emitting diode display of claim 1, wherein thedriving voltage has a constant voltage level.